Method of perforating one of a plurality of parallel pipe strings



OCt- 10 .1961 iF. M. :MCGEHEE METHOD -zoF PERFORMING foNE 10F A PLURALITY y0F PRLLEL PIPE STRINGS Filed not. v2:5, 195e JNVENTOR. YFlwzLEY M. MCGEHEE,

ATT R EY.

nited States METHOD OF PERFORATING ONE OF A PLU- RALITY OF PARALLEL PIPE STRINGS Farley M. McGehee, Genoa, Tex., assignor, by mesne i assignments, to Jersey Production Research Company,

Tulsa, Okla., a corporationof Delaware Filed Oct. 23, 1958, Ser. No. 769,143 6 Claims. (Cl. 166--35) The present 4invention may be briefly described as av method of completing a well which penetrates a plurality of productive zones and has a plurality of parallel eccentric coextending pipe strings cemented therein in 'which an opening is formed in a selected one of the pipe strings in a selected of the zones while avoiding the formation of an opening in other of the pipe strings and then forming a passage iiuidly communicating the selected zone with the opening in the selected pipe string through the cement whereby fluid is owable through the opening in the pipe string and the passage between the selected zone and the selected pipe string. Thus, the other pipe strings are maintained free of any opening in the selected zone.

The opening may be formed in the selected pipe string by employing a bullet gun using a deiiecting type of bullet, using a chemical perforator which jets a stream of chemical against the Wall of the selected pipe string` or by employing wire line tools which cut, punch, mill, or otherwise form openings or perforations in theselected pipe string only. Such devices are well-known in the art and involve cam type punches and the like.

Communication between -the opening and the zone of interest which may contain hydrocarbons such as oil and/or gas is suitably established by treating the cement through the openingwith an inhibited acid which will dissolve the cement-but which will not attack the metal making up the selected and other pipe strings in the well. It may also be possible to establish fluid communication through the opening and the zone of interest by employing the so-called fracturing technique by way of which fluid pressure is exerted on the cement and the earth zone through the opening to cause formation and opening up of fractures in the cement and in the rock making up the earth zone to be exploitedfor oil and/or gas production.

The present'invention will be further illustrated by reference to the drawing illustrating a preferred mode in which:

FIG. 1 shows the perforation of a plurality of spacedapart earth zones; Y

FIG. l2 illustrates the acidizing of a selected 'zone to form a passageway in the cement; and

FIG. 3 illustrates the simultaneous production of both zones. n t i v Referring now to the drawing in which identical 'numerals will be employed to designate identical parts, numeral 11 designates a well bore having la iirst pipe string 12 and a second pipe string 13 cemented therein with cement 14. The pipe strings V12 and 13 are iluidly interconnected by a iluid interconnecting means `15 forming a passageway 16. The lower end of the pipe string 12 is closed by metal plug or plate 17. Lowered and suspended in the pipe string 12 on a wire line or cable 18 is a mechanical or chemical perforator 19 or a perforator firing a deflecting bullet which punches, mills, or dissolves openings 20 in the pipe string 12 only, the perforator 19 being of a nature that openings will be formed only in the wall of the pipe string 12.

Lowerable through the pipe string 13 on a wire line or cable 21 is preferably a bullet or shaped charge perforator 22 provided with bullet guns or shaped charges 23 which, when fired, forms perforations 24 in the pipe string 13, pierces the cement 14, and extends into the lower earth zone, formation, sand, stratum, or horizon 2S from which hydrocarbons may be producible. While a bullet or shaped charge perforator 22 is preferred, the chemical or mechanical perforator is not excluded from use in the zone 25.

The zone 25 is separated by nonproductive zone 26 from an upper productive zone 27 in the well bore. It is to be understood that zones `25 and 27 are given by way of illustration since a plurality of productive zones greater than two -may be simultaneously produced in accordance with the present invention, utilizing a plurality of pipe strings such as 12 and 13, each producing from a separate Zone.

Once the openings 20 have been formed in the pipe string 12, it is necessary to form a passage through the cement 14 and to this end operations are so conducted to form such passage. Referring particularly to FIG. 2, a tubular member 23 is lowered on a wire line such as 18 and positioned in a landing nipple or suitable supporting or anchoring means 29 in the tubing 12 above the fluid interconnecting means 1S. The tubular member 28 is suitably sealed by means of a sealing means 30 on its upper end and by sealing means 31 on its lower end such that fluid is ilowable through the tubular member 28 but iiuid maynot be ilowed through the passageway 16. yInhibited hydrochloric acid having a strength in the range from about 5 to 25% but which may range up to 38% HC1 is owed down through the pipe string 12 to form a body of inhibited hydrochloric acid 32 which flows through the opening 20 and form-s passageways 33 out to the formation or zone 27 by dissolving out the cement 14. The presence of fthe metal plate or plug 17 prevents the acid from attacking the cement through the bottom of the pipe string 12. The passageways 33 are'extended until fluid communication is established with the formation or zone 27, as shown more clearly in FIG. 3. Once the fluid communication has been established between the pipe string 12 and the formation orzone 27, production may be initiated from the zone 27, which will cause the inhibited acid 32 to be displaced upwardly through the pipe string. Simultaneously, production may be obtained from the zone 25 through the perforations 24 and up the pipe string 13, as shown in FIG. 3.

While the body of acid 32 may suitably be displaced by the production iiuid, it may be preferred to circulate it out by replacing the tubular member 28 with a tubular `longer tubular member, the fluid may be circulated out 28aud omitting the seal 31 such that by employing a by owing fluid down the pipe string 13 to displace the bodyl of acid 32 up through the pipe string 13.

Inhibited hydrochloric acid is a well-known article of commerce and acids of varying strength may suitably be used. The acid strengths may range from strong acids having about 43% HC1 by weight down to about 5% HC1. The inhibitors employed may include arsenic acid; arsenic trioxide; furfural; furans; nitrogen bases such as aniline, pyridine, quinoline and the like; organic sulfur compounds and acid sludges derived from sulphuric acid treatment ofY petroleum fractions. Crude petroleum phenol extracts such as described in U.S. 2,380,254 may also be used. Naphthenyl amines and salts thereof as described in U.S. 2,818,383 are also suitable. Other inhibitors may include by way of illustration and not by way of limitation alkali metal dehydrated phosphate derivatives such as described in U.S. 2,813,075, rosin amine derivatives as described in U.S. 2,75l8,970,.aliphatic thiourea compounds such as described in U.S. 2,799,- 648, quaternized normal heterocyclic polyoxyethylene derivatives as described in U.S. 2,814,593, and `other similar corrosion inhibitors may suitably be employed. For example, polyalkylene glycols, as described and claimed in U.S. 2,799,649, may be usable in the practice ofthe --present invention as corrosion inhibitors.

The present invention has been described and illustrated with inhibited -acids being used to form a passage through the cement. It is also contemplated in the pract-ice of the present invention that a fracturing technique may Abe used for forming a fracture or passage through the cement and into theformation. In this type of operation, a procedure such as described with respect to FIG. 2 would -be employed with the exception that a low fluid-loss fracturing -liuid-would be employed and pressure would be exerted through the openings 20 on the cement 14 to form fractures or passages Vthrough the cement 14 into the formation 27. The technique of fracturing formations is well-known and involves preferably the employment of a low fluid loss fluid on which pressure is fexerted to form thefracture or to open an existing minute fracture of crevice for fluid communication. This technique may be applied to communicating between the perforation 420 and the rformation of zone 27 to form an opening or channel such as^33 described in FIGS. 2 and 3. The sequence of steps is substantially as described with respect to FIG. 2 with sufficient hydraulic pressure being exerted on the fracturing uid, which, rather than being a low uid loss fluid, may be water, crude petroleum and/or its fractionsor any one of the many materials now being used for this type ofV operation.

In the description taken with the drawing, the yinvention has been described and illustrated showing a plurality of fluidly interconnected pipe strings. The invention may equally be practiced employing `a plurality of pipe strings in a Well bore which are not 4iluidly interconnected. Therefore, it is contemplated that this invention will include well completions either in iluidly interconnected, parallel pipe strings, or in parallel pipe strings which are not uidly interconnected.

Also, the invention has been described and illustrated .by reference to a well having two substantially parallel pipe strings therein. The invention is also kapplicable where three, four, or more pipe strings are arranged .and/r cemented in a well 'bore whether they be iluidly interconnected intermediate their ends or not. Reference has been made in the description taken with the drawing to the use of mechanical type ofperforators These perforators usually operate yon a wedge principle with one wedge moving vertically to drive another wedge laterally to which the punch or vmill Ais connected. .'Ihus the vertically movable wedge is actuated by aA-mechanical jar and is then exerted on the laterally movable wedge or by an explosive force-to cause ,perforation of the pipestring and formation of an opening therein. Likewise, these perforators may be actuated by earn action.

The invention'has also been illustrated by reference Vto Producing formation fluids but it may equally be practiced in injecting fluids into 4the formation or zone. Thus, after fluid Icommunication `has been established,

3,003,556 f' 'e f operations such as well stimulation, including acdizing, injecting-ofsurface-active agents, cementing, secondary recovery where water and/or other uids such as gas and the like are introduced into the zone or formation of interest, may be practiced. These several operations are given by way of illustration and not by way of limitation.

The nature andobjects-of the present invention having been completely described and illustrated, what I wish to claim as new and useful and secure by Letters Patent is:

1. In a well penetrating a plurality of productive zones and having a plurality of parallel adjacent eccentric coextending continuous metallic pipe strings, separated from Veach other by a cement sheath, the method lof completing said well which comprises selectively perforating the metal wall of a selected of said pipe strings in any direction in a selected of said zones while maintaining the cement around said selected pipe string, and the metal wall of other of the pipe strings, free of any perforation in said selected zone, and then forming an vopening in any direction through the cement in alignment with the perforation in said selected pipe string to fluidly communicate said selected zone through said cement with the perforation in the selected pipe string whereby iluid is ilowable vthrough said perforations in said vselected zone and between the selected zone and the selected pipe string.

2. A method in accordance with claim 1 in which the selected pipe string is selectively perforated by punching through the metal wall of the selected pipe string.

l3. A method in accordance with claim l in which the selected pipe string is selectively perforated by chemical reaction with -the wall ofthe selected pipe string.

4. A method in accordance with claim 1 in which the opening in any direction through the cement is `formed by dissolving a passage through the cement with acid.

5. A method in accordance with claim l in which the opening in any direction through the cement is formed -by applying sufficient fluid pressure to the ycement to form `a fracture through the cement.

6. A method in accordance with claim 1 in which the metal wall of another of said pipe strings is selectively perforated in any direction in a second selected zone vertically displaced from said selected of said Zones while maintaining the cement around said another pipe string and the metal wall of other pipe strings free of any perforation in said second Selected zone, and then forming an opening in any direction throughthe cement in alignment with the perforation in said another pipe string to fluidly communicate said second selected zone through said cement with the perforation in said another pipe string.

References Citedin the tile of this patent UNITED STATES PATENTS 2,193,807 Dieterich Mar. 19, v194() 2,201,290 4Greene May 21, 1940 2,215,913 Brown Sept. '24, 41940 2,259,564 Holland ,Oct. 21, 1941 2,436,198 Cardwell et al AFeb..17, 1948 2,642,142' Clark June 16, 1953 2,725,942 McCullough Dec. 6, `1955 2,785,754 True .Mar. 19, 1957 

